This invention relates to a method and apparatus for protecting a rotating magnetic recording medium (hereafter referred to as a "magnetic disk") in a magnetic recording/playback system which is capable of recording a signal on any track on a magnetic disk, or of playing back a signal from any track on the disk, or of both these recording and playback operations, by moving a magnetic recording/playback head in the radial direction of the magnetic disk.
Electronic still camera systems have recently been developed. These systems combine an imaging device such as a solid state imaging element or image pickup tube with a recorder that employs an inexpensive magnetic disk of a comparatively large storage capacity as a storage medium and operate by electronically imaging a subject, recording a still picture of the subject on the magnetic disk and reproducing the recorded picture by a separately provided television system or printer. A video magnetic recording system has also been realized in which a still picture recorded on a visible recording medium such as ordinary film or photographic paper is imaged and recorded on a magnetic disk.
In systems of this kind, a video signal is recorded on the magnetic disk or read from the magnetic disk not by merely contacting the magnetic recording/playback head with the recording surface of the disk lightly but by pressing the head against the disk surface so strongly that the disk is partially deformed. Since the magnetic disk has some flexibility and therefore returns to its original state even when somewhat deformed, no problems are encountered even though the magnetic head is pressed against the rotating magnetic disk at recording or playback. However, when rotation of the magnetic disk is halted and the magnetic head is held in abutting contact with one location on the stationary magnetic disk, the portion of the disk in contact with the magnetic head becomes permanently deformed and is scarred or left with an impression of the head if such contact is allowed to continue for an extended period of time (e.g. for several hours to several days). This is especially likely to occur in the abovementioned video magnetic recording system or video playback system in which, after recording or playback, the system power supply is turned off without returning the magnetic head to a predetermined origin, e.g. a home position. The magnetic head remains on the disk track at which recording or playback was last taking place because power for returning the magnetic head to the origin position will no longer be available if the power supply is turned off, and because the magnetic disk will also be at rest.